Hi Robin, hope you're well! Nice video/coverage on this topic that's near and dear to my heart. I'm glad to see EFR still getting some love now ~14 years after its release and I'm glad the turbo (and the support staff) have treated you well. It's also fun to see that MatchBot is still being used. Good luck on the mountain in 2025!
I worked at BorgWarner a 5+ years ago and this brings back a bit of nostalgia talking about properly engineering a turbo setup (rather than "bigger turbo better, smaller turbo less lag"). One thing I'll note is you mentioned that Garrett has higher efficiency numbers. Comparing those numbers across brands is very tricky to do, because everybody's testing setup is different and isentropic efficiency is a tricky quantity to measure. Even at BorgWarner, there were known discrepancies between different different testing chambers (and those differences were accounted for in our testing results). Application engineers at some point complained that our reported efficiency numbers were lower than competitors, even though customer got better performance with our turbos than the competitors in the customer's own dyno setups. Not saying that's always the case with BorgWarner stuff, just something to keep in mind when comparing across brands.
@zibingotaeam3716 I really doubt Porsche is relying on a turbo supplier's claimed hp figures for their cars... no it's just an under promise, over deliver situation.
AKA typical Germans. It reminds me of the Ruf Yellow Bird with a (LAUGHABLY LOW) advertised horsepower level of 385. So German. It's why I have spent so many hours on MatchBot, and so very little on whatever the competitors have put out. German companies do not assume their audience/customers are idiots.
It's awesome hearing this design analysis from someone who can read a chart of total pressure ratios and talk about those sorts of technical details. A lot of bespoke automotive design that's open to the public is much less rigorous, so it's wondeful that you share this so freely!
@cconnon1912 go for it man, I have had similar aspirations since I was young and now as a 21 year old engineering student I can barely believe sometimes how close Im getting to the dream. Just keep immersing yourself in information about mechanics and physics related to making a vehicle go fast, that and some determination. Also as a sidenote, the budget isnt what you or I would call reasonable, its still a big ass lump of money, but still something you can afford if you dedicate yourself or sell your soul to a big global manufacturer.
I’ve never sized a turbo (and I doubt I ever will), but this seems really comprehensive, and it’s from an obviously knowledgeable expert. Thanks for sharing your wisdom, Robin!
I'm having a flashback to Bonneville 2001. I had a big argument with the team owner about what was required to get an oversized turbo (his idea) on the sweet spot of the map. He was unable to put his ego aside and it cost him. Later that year he implemented my recommendations and went 14 mph faster.
Thank you so much for sharing the dev and build process with us. It’s refreshing to hear someone address something within a real budget but also has experience enough to pursue known good products, practices and explain why and how they got there. I appreciate the bit about the turbo SYSTEM selection, as treating the whole thing as a system (gates, housing, blowoff) lead to weight and packaging decisions.
Hi, Robin. I just wanted to thank for doing these. I just found them, and subscribed immediately. Your information is clear, concise, and understandable for a racer type from back in the 70s. I found you through Superfast Matt, so I thank him as well. 👍
Hi Robin. I'm enjoying your video series immensely. I ran a variable geometry turbo in my UK hillclimb car and after several iterations of the vane mapping it improved the lower rpm torque curve and response of the engine. I used an old technology Garrett VNT28 on a Cosworth YB. Rather than the usual approach of 400 bhp from a larger laggy turbocharger I decided to try the VNT 28 which topped out at 315 bhp but was on full boost from 2500 rpm. It made the car much more effective on UK hillclimbs. I now do a few more sprints, so have moved to a Borg Warner EFR 7163 twin scroll. As you know, this is a much more modern design and certainly more efficient. The pick up at low revs is not so good as the VNT but even so I'm at full boost at 3250 rpm and the extra bhp is useful. I think the swing gate variable geometry idea you have is definitely worth pursuing. I am sure the low end response that is so important in hillclimbing will pay dividends. Are you going to use an electronic wastegate actuator? Good luck with the project!
Highly informative and well presented. As always, I enjoy your content. Keep up the good work and thanks to SuperFast Matt for turning me on to you and your passion project.
What about pre turbo throttle body? It worked for ww2 planes, 80s F1 race cars and current ones also. I encourage you especially to look up ww2 planes stuff because of the altitude change, they would put too big compressors for the sea level and thanks to pre compressor throttle they coud run at that sea level but have more power up top. As for F1 cars they did that to eliminate turbo lag by having turbos run in vacuum so they would run at high rpm always. Only con is that oil seals are made to work under pressure so you would burn some amount of oil at closed or partially open throttle but on your case i dont see an issue with that.
Good idea i saw a video about russian swirl throttle by maisteer and was wondering why body is using it anywhere i hope he answers this question because it seems like no branier.
Another attribute of the EFR range and BW turbos in general is how robustly built the turbos are. The bearings are super reliable as well as the seals are can withstand extreme oil pressures and temperatures. There's a reason its the turbo of choice for so many street driven rotaries. Even used in Indy Car, and is now in the new ZR1 too.
I think the hardest thing to learn in any discipline is the right way to think about real complex problems from the high level, so you can actually apply all the lower-level textbook stuff. Thanks for sharing all your insights.
Kinda, that stuff comes on like a switch and can get explodey if done wrong or the system malfunctions. I like it though and is next on our list to use after switching twin scroll and regular antilag
A question, you have been speaking about running the engine on the dyno a couple of times. Since you are going to run it at altitude. Do the dyno shop have equipment to reduce the air pressure to what you are going to run at? Where I’ve been dynoing my engines the shop have a big centrifugal Kompressor that they attach to exhaust, inlet, crankcase and all the “holes” that is significant to simulate different altitudes
Simulating aire pressure is easy enough, you can restrict the inlet, and yes you can attach a large compressor yo the exhaust to simulate low pressure altitude. The difficult part is temperature at the inlet which is a large factor of density. Trying to lower the inlet temperature to what you may see at altitude is difficult.
Super interesting. Would be fun to see how the area on the compressor map used area for your application moves depending on altitude. More editing needed ofc, so less car-engineering. I get your tradeoff. Keep it up!
My initial thought was VNT. I had one on my golf (mk1 1300!!) in about 2000(ish). The performance really was staggering. Lag and boost threshold of a T2 but good for well over 300. That turbo looks pretty trick. Materials certainly have moved on since I was playing with them. Great stuff.
@@heem6619 that was always a concern but never a problem. Ran them on all sorts - R5, scooby and even a pair on a VR4 (had fun getting the plumbing right!). Never had a failure.
@thesendyclub please help do so!!! there is also 'turbo-supercharching' which is 1st stage super charger and a 2nd stage turbo like on Alison v1710 and Pratt & Whitney R2800 engines
@@thesendyclub please help do so!!! there is also 'turbo-supercharching' which is 1st stage super charger and a 2nd stage turbo like on Alison v1710 and Pratt & Whitney R2800 engines
Wouldn’t it be an easier anti-lag strategy to use nitrous intermittently (since the rules don’t prohibit its use)? You can use as much or as little as you want and it’s very effective at increasing low speed torque production even below the boost threshold RPM / load…
Have you considered making use of a rocket anti-lag system to help deal with turbo response? Would be awesome to hear your thoughts on this type of system.
It would essentially impossible to find any commercial CVT capable of running this HP, at a weight he would accept. I think it would be technically possible, but would cost a lot in development time. I can picture some very creative solutions splitting torque on planetary’s, and using hydraulic or electric motors to modulate the speeds of each the planetary components. AGCO does this in high HP tractors with remarkable efficiency, the challenge would be converting it from a high torque system to a higher RPM light weight system. th-cam.com/video/dgtIKMAjvFI/w-d-xo.html Something like this would not require the extra weight of batteries, but would still be significantly heavier than a conventional gear box.
@OwenDarrach Williams were developing a cvt in Formula 1 back in th 80s or early 90s but they never used it because it got banned before they got to use it. It's a shame they didn't get to develop it more because they might have done a better job at it than the ones car manufacturers are doing now.
@@Paul-ik8fm I have heard about that, but as far as I have heard they were never able to have the compression “belt” last long enough. Banned or not I was under the impression it never matured enough to actually race after considerable development. Most of what I read also indicated they had they were testing at closer to 850 hp, adding another 150 hp would have only made the challenges more prevalent. There are lots of other ways to accomplish the CVT effect, was my main point. The AGO concept would theoretically mean the electric system could be very small relative to the total HP. Most of the easy to find content on that thing lacks a lot of technical / engineering depth. If you have a comprehensive source I would love to read more on it.
On the twin scroll turbo elmer racing makes a turbo collector that has a wastegate on one scroll pre turbo to have the same effect as the flap would have, they rate it to 1000hp too
@@playyourturntodieatvgperson I mean it wouldn't have to be 100% accurate as it should be playable half an hour at a time. But it may be more feasible by giving it a basic modeller for bodywork, chassis, suspension and engine, and few simple validation tools that write the components files. So it doesn't have to simulate bodies like BeamNG but it still requires some craft to come out with a frame, the headers, the wings, etc. Either starting from a fictional production car or engine, or by scratch
This is one of the reasons piston aero engines were often turbo-supercharged, because boost targets were sometimes unachievable at altitude with turbocharged exhaust mass air flow.
Great video! What’s your plan for controlling the turbo speed? Are you considering using something on the cold side, like a more adjustable blow-off valve, similar to what’s used in drag racing, to improve spool time and refine power delivery more accurately?
Maybe more topical for another video but what do you think of the Enviate aero concept/overall platform concept? How constrained is the current concept by tire and wheel loading?
Are there any aftermarket electric turbos coming on the market yet? I mean the kind like I believe Porsche are using where there’s an electric motor sandwiched between compressor and turbine to assist with spooling up during shifts and low RPM times?
well the racecar won't be a hybrid, so i think it wouldn't really be worth it to use an eturbo. adding in all the necessary electronics would add a lot of weight on a pure combustion car
Great video, thanks for sharing. One query, for open exhaust systems with aftermarket turbos with integral wastegates, those can sometimes have trouble maintaining boost control at higher rpm. Are you confident that the integral wastegate of your selected turbo will have enough flow potential to adequately control boost at high rpm?
Only as a thought sort of questions but where do you decide to start with something and do you do it in steps or do you get a grand plan then try and execute it at once?
Could you talk about your anti lag system? I saw a video from Stav-tech where he added an throttle body on the intake of the turbo housing. To help prevent the turbo from slowing down. And he found that the responce time really decreased! My question is if you know this concept, and if you have Thaught about it or have some thing better in mind. I find this really interesting and not talked about enough. Great video again! :)
Hey Robin, was there consideration of a hot V setup? With your custom built* motor, would there be the possibility to effectively swap the heads? Obviously would need a new block to match water and oil passages, but would that be un-feasible? Would the weight savings (less exhaust piping, more CF intake piping) be too overshadowed by complexity?
The latest Porsche design does this and has some major emissions benefits. The excess compressed air is used to keep the catalytic converter happy at stoic under all loads and RPMs. That way the engine can run rich and make power without an emissions penalty. I don’t think it would be worth the weight penalty or complexity on this Pike’s Peak car.
Is a compound turbo set up for both low end quick spool and high-end power to complex and unreasonable on the mountain? Edit: I see the variable housing turbo accomplishes similar with less complexity.
Compounds on a gas engine, it takes really high boost. You only get so much exhaust energy, that energy needs to be split between the two turbos. Most gas engines will not be able to utilize a compound set up until it's very high h.p. (north of 4o psi in most cases )
Have you asked borg if they can do a s368sx-r (13807105053) comp wheel in the 9274 assy? Similar compressor map with a smaller compressor. I have been trying to get a source for s258sx-r compressor wheels to throw one in a 7670 to no avail but I'm sure you wouldn't have any issues considering your collaboration with the 8370.
Hey mate , I really like the show and what you do it's great . Did you run traction control on the wolf and will you do it on the new car . Is there any benefit on the mountain with the power differences with altitude. I see a few drag and roll racers using it really well over here . Obviously the racing and cars are fields apart but just wondering if you use it and if so how you do it
Hi, regarding downforce and wings. I haven´t really seen this solution yet and i ask myself why shouldn´t it work? Passive DRS: so the splitter and the rear wing could be front pivoted and held up in the back by f.e. gas struts, so it "straightens" with faster airflow. Like that the downforce could be held kind of "costantish" at different speeds while also limiting the effects on ride height and wheel load at high speeds? Is there a reason there is no such system widely used?
Fast corners and braking from high speed with lower downforce doesn't make much sense, that's why DRS is active so it can be disabled once you near a corner.
Its like building a turbocharged aircraft but actually more difficult. I only start with a low pressure ratio of 1.5 and rpm remains the same. Having a high pressure ratio and with variable rpm on a single compressor map is harder than most people realise. I was designing a high altitude aircraft to fly at 26km, and that needs 4 stage compounding for just 300kw with a crankshaft driven supercharger with a 600mm impeller.
I’m wondering if there are engine dump cells that are capable of controlling the ambient/atmospheric air pressure? Or if that would even be helpful for something like this.
the bit about de-tuning the aero package at speed is very interesting, but how about a suspension linkage that reduces the angle of attack when the suspension is compressed? this would de-couple speed and down-force a bit and reduce the issues of drag and stress at high speed while preserving low-speed performance. probably forbidden in most regulations but for this particular event it might fly
Certainly there's a gain to be had in this part of the system. Wave physics make it very tricky and require a great deal of resources to get a small improvement. In other words, this is something more suited to a team with a much bigger budget. To keep from being spread too thin, you'd need at least 12 engineers working crazy hours and one of them would need to be a very experienced aero/thermo specialist. Maybe hard to believe, but at the peak of development some larger teams can have as many as 60 people working on drivability issues!
it looked like you considered parallel twin turbos. did you think about doing sequential or series turbos at some point and could you explain why a single is superior?
Would there be advantages to a hot V configuration with a large single turbo? What fuel are you planning to use? Methanol would be good for performance but the volume you need to carry might be an issue. Nitrous ?
How are you determining what the maximum Fz is before mu drops so much that Fy no longer increases with increased normal load for the tire (Load Saturation). Do you have data from tire testing or guidelines from the manufacturer? Thanks!
Yokohama provide us with data, but it doesn't go high enough in load... It's more about keeping the car off the ground at Pikes. Those tires will take it
Very long and drawn out question but, when considering building a vehicle for the first time without much prerecorded data, I understand that it is much more difficult to make decisions like this. How would someone like me go about finding a good guesstimate on power band and average rpm range/vehicle speed? Other people’s engine/gear ratios and car setup is different and may reach different speeds in the same straights or between corners. I find it difficult to understand where to sacrifice power for response and by how much especially with bespoke builds.😢I might be overthinking but just buying a different turbo might mean changing all piping sizes and possibly routing and weight and space and plumbing which can become a very expensive and consuming ordeal.
Having no wastegate on the turbo hot side and dump the boost cold side with a DBW throttle body will give the fastest response and ultimate boost pressure going up the mounting Ash
@@Surestick88 it's being used like this in drag racing at the moment so they can get the RPM on the turbo off the line and down the track. The other thing to do is put a Throttle body Infront of the turbo intake that closes when off the throttle making the compressor run in vacuum and not dumping the boost. That way the turbo keeps the RPM ready for snapping the throttle open and no turbo lag 😉 Was used in the 80s and still used like this now in F1
2003 Ford Focus RS WRC used a 45-liter titanium tank to store boost pressure and release it on demand. Does Pike Peak Rules have anything to say against it? 🤔
Any consideration of compound supercharging systems (inc turbos) like they used to use in old WW2 planes and some rally cars? I'm guessing it's a case of complexity and weight isn't worth it
How much data do you have logged for your previous runs up the mountain? Seems like you could plug in the stats for any (or every) particular moment into Matchbot to simulate a previous run. Then experiment with engine and turbo parameters to compare power at each moment, then compare the curves. Throw in what you know about weight and gearbox, you can probably make an educated guess about run time impact. I know different cars will have different runs, but I bet the throttle inputs and environmental conditions will be close enough that you could optimize against that previous run. Like you say, we all want to plan for WOT max boost situations, which is a pretty small fraction of the run. Imagine a dyno that runs the pedal input, and increasingly limits the intake pressure to simulate the mountain.
Well it's essentially a huge pressure tank, if we're down to shaving single digit kilograms to save on weight I don't see it make sense on a car of that size
Compound turbos could give you the full broad curve with the altitude change. They are still not well understood by many. I've been looking at doubles and even triples for aircraft up to 35k. The compounds will let you spool easy and still give you the flow up top. There's a couple guys that have mastered them in drag racing. I think both have been interviewed by Andre from High Performance Academy.
Intercoolers? Any plans to do stuff like, dry ice cooled system. Might be more of a thing for the Diesels running their absolutely stupid boost level's.
I don't know much about aerodynamics and I know even less about how permissive ground effect is, but if it operates on the basis of the air going faster under the car, then wouldn't it be the ideal place for air intake if you're running a turbo ?
The air going faster reduces its pressure because Bernoulli. You'd be pulling in air at lower pressure. There would also be the issue of all the dirt you'd have to filter out.
@@Surestick88 well yeah, it only creates downforce because the pressure is lower but I thought the goal of a ram intake was to be shaped in such a way that you convert that velocity back into pressure, although I guess at that point you gain nothing from placing it within the floor... The dirt on the other hand I completely forgot about
The ram air intake has to be in either free stream air like what you see in open wheel racecars, or where you get high pressure on the car aerodynamically, like in front engine race cars where they collect air density from the front of the radiator, for best results. You don't want foreign material in your race engine, that's for sure.
Beware the v band flange taking weight of turbine housing, your material properties are going to be different at 1000C and distort and leak if not considered. Balance the bracing needed vs flange type. But I’m sure you knew that
Awesome project I am very surprised that a v-band turbine housing is the standard of the industry. Those T4/T6 flanges just make a terrible, hard to deal with joint. Tial used to make nice quality stainless v-band turbo housings- of course no doubt they weren't as efficient as the housings developed by the turbo manufacturers
Coming from the Honda motor in the Wolf and now to a V8, might you consider both of these elements combined in the future with the Neutron Engines K48 ? Personally i can see it being a hit if tested successfully
You can get a turbo spooling pretty quickly, it's just that a single package is going to be a compromise every time. A system that would account for more rpm ranges would be heavier, more costly, more maintenance intensive, and more complex, and maybe that's what you want to avoid depending on the use case
Making an anti-lag setup that is motorsports-grade in quality with time AND money constraints is extremely difficult, especially if what you're dealing with is a hillclimb with huge changes in air density. Something that will last for a whole program without costing much and breaking stuff is gonna be difficult. Mind you that this team is not backed by a big manufacturer. Porsche excelled with their Pikes Peak program due to their excellent engine management on the GT2 RS.
When running on a restricted development budget and one event a year. Would it not have been better to build a new wolf , and address any short comings as opposed to a ground up build which could potentially lead you down an engineering dead end . Or . Do you feel you have already done this . As an amateur that's developed my own competition machinery in the past. I feel that could be a less perilous approach
He already talked about the Wankel's inherent lack of thermal efficiency. More fuel to carry, just for it to dissipate into heat. It's also notoriously hard to cool conventionally with water, and depending on the oil to cool the engine down isn't really a good idea.
i don't get the point. call me stupid at will, but only if you can clearly elaborate and prove why you think so. so here is my thinking : find the peak toruqe of your engine running n/a. slap on a supercharger and gear it to produce at about say 1.2:1 pressure ratio at that rpm. what will happen is, a supercharger (positive displacment pump style) will not have a constant pressure ratio. as the engine volumetric efficiency changes, so will the pressure ratio of the supercharger. now you can use a larger turbo, have less lag as the supercharger will be sucking air in and help that thing to spool, you will hit your total pressure ratio sooner allso. say you need something like 2 bar or a pressure ratio of 3:1 . your supercharger will produce a least 1.2:1 , so the turbo doing just 2.5:1 pressure ratio in the worse case. that you get sooner. a larger turbo is less restrictive. a blower running on low boost ain't taking that much of power to run. you can bypass the supercharger, if you feel like, on the fly. you can whit some ingenuity do what aircrafts do and have a 2 speed supercharger, as you climb up it may or may not be benefical its not for me to decide. it be a nice thing to see some talk about compound charging .
What you describe is a complicated, heavy system. A well sized single turbo is "good enough" and has been proven over and over to be faster on the mountain. One of our team members has made several compound systems on the request of teams. They now run single turbos. Diesel is a different situation though...
@@thesendyclub lets assume I digest the single turbo for the simplicity of Just being a single turbo. Assuming /rightfully/ that 2 or more smaller turbo chargers would only add complexity and yield about as much extra as a nothingburger. That part is clear. What never was clear , is whats complicated in 1 more pulley and a belt, and 1 more pipe. Specially when that yields a flatter tourqe cure and a greater usable rpm range , and additional power, and less lag , and ability/necessity of using a bigger and less restrictive turbo. Thats the part what I would be interested in. Surely diesel is different. Won't knock from higher boost. That I give you. But apart from the need to keep the boost from the system in check , why on earth would a blower + turbo be so big deal vs Just a turbo , from complexity point of view ? Its a relatively simple device, a block that has a spinny thing that is driven by the engine via a belt , it has a port to suck from , and a port to blow to. You get yay amount of boost depending on 2 things , one is volumetric efficiency and the other is drive belt ratio. In principle , the slower the blower runs the more efficient it is. And that gives a lot of yeehaa.
You could probably test on Umling La in Ladekh India in the Himalayas. Now closed to the public, paved, warmer climate, goes over 15k feet. Shhh, don't tell anyone
Hi Robin, hope you're well! Nice video/coverage on this topic that's near and dear to my heart. I'm glad to see EFR still getting some love now ~14 years after its release and I'm glad the turbo (and the support staff) have treated you well. It's also fun to see that MatchBot is still being used. Good luck on the mountain in 2025!
Hey Brock, thank you for doing such a great job with the turbo!
I worked at BorgWarner a 5+ years ago and this brings back a bit of nostalgia talking about properly engineering a turbo setup (rather than "bigger turbo better, smaller turbo less lag").
One thing I'll note is you mentioned that Garrett has higher efficiency numbers. Comparing those numbers across brands is very tricky to do, because everybody's testing setup is different and isentropic efficiency is a tricky quantity to measure. Even at BorgWarner, there were known discrepancies between different different testing chambers (and those differences were accounted for in our testing results). Application engineers at some point complained that our reported efficiency numbers were lower than competitors, even though customer got better performance with our turbos than the competitors in the customer's own dyno setups. Not saying that's always the case with BorgWarner stuff, just something to keep in mind when comparing across brands.
Is that why Porsche always underpromises and overdelivers? If memory serves, they usually buy BorgWarner turbos.
@zibingotaeam3716 I really doubt Porsche is relying on a turbo supplier's claimed hp figures for their cars... no it's just an under promise, over deliver situation.
AKA typical Germans. It reminds me of the Ruf Yellow Bird with a (LAUGHABLY LOW) advertised horsepower level of 385.
So German. It's why I have spent so many hours on MatchBot, and so very little on whatever the competitors have put out.
German companies do not assume their audience/customers are idiots.
@@exploranator kinda inefficient, when you think about it - their customers end up with more performance than they may have bargained with.
I assume that the maps are drawn under a standard atmosphere of 1 bar 15 degrees?
It's awesome hearing this design analysis from someone who can read a chart of total pressure ratios and talk about those sorts of technical details. A lot of bespoke automotive design that's open to the public is much less rigorous, so it's wondeful that you share this so freely!
Amen, I knew this series was going to be a treat when he properly explained the relationship between torque and power
Design, build and race, Pikes Peak hillclimb race cars and win on a reasonable budget? I kinda want to grow up to be you. 😅
Then do it! I believe you can. Please post when you do so we can all support you!
Find a local team and volunteer
@cconnon1912 go for it man, I have had similar aspirations since I was young and now as a 21 year old engineering student I can barely believe sometimes how close Im getting to the dream. Just keep immersing yourself in information about mechanics and physics related to making a vehicle go fast, that and some determination. Also as a sidenote, the budget isnt what you or I would call reasonable, its still a big ass lump of money, but still something you can afford if you dedicate yourself or sell your soul to a big global manufacturer.
I’ve never sized a turbo (and I doubt I ever will), but this seems really comprehensive, and it’s from an obviously knowledgeable expert. Thanks for sharing your wisdom, Robin!
I'm having a flashback to Bonneville 2001. I had a big argument with the team owner about what was required to get an oversized turbo (his idea) on the sweet spot of the map. He was unable to put his ego aside and it cost him. Later that year he implemented my recommendations and went 14 mph faster.
Exactly!
I absolutely love these videos. It’s cool to hear an experienced enthusiast explain the thought process for a competition like this!
Thank you so much for sharing the dev and build process with us. It’s refreshing to hear someone address something within a real budget but also has experience enough to pursue known good products, practices and explain why and how they got there. I appreciate the bit about the turbo SYSTEM selection, as treating the whole thing as a system (gates, housing, blowoff) lead to weight and packaging decisions.
Hi, Robin. I just wanted to thank for doing these. I just found them, and subscribed immediately. Your information is clear, concise, and understandable for a racer type from back in the 70s. I found you through Superfast Matt, so I thank him as well. 👍
Hi Robin. I'm enjoying your video series immensely. I ran a variable geometry turbo in my UK hillclimb car and after several iterations of the vane mapping it improved the lower rpm torque curve and response of the engine. I used an old technology Garrett VNT28 on a Cosworth YB. Rather than the usual approach of 400 bhp from a larger laggy turbocharger I decided to try the VNT 28 which topped out at 315 bhp but was on full boost from 2500 rpm. It made the car much more effective on UK hillclimbs. I now do a few more sprints, so have moved to a Borg Warner EFR 7163 twin scroll. As you know, this is a much more modern design and certainly more efficient. The pick up at low revs is not so good as the VNT but even so I'm at full boost at 3250 rpm and the extra bhp is useful. I think the swing gate variable geometry idea you have is definitely worth pursuing. I am sure the low end response that is so important in hillclimbing will pay dividends. Are you going to use an electronic wastegate actuator? Good luck with the project!
I’m really enjoying this journey. Kinda neat to hear why decisions get made and what’s to come.
Highly informative and well presented. As always, I enjoy your content. Keep up the good work and thanks to SuperFast Matt for turning me on to you and your passion project.
You called us "Normoes" but we actually prefer the term "Normies" this side of the pond thank you very much.
No he didn't. He didn't talk about muricans, he did talk in general. You're not the center of the world ;-)
@@heikoscheuermann Riddle me this, normo: where is pikes peak?
@@RedlifeWoW 🤦
🤣🤣🤣🤣
What about pre turbo throttle body? It worked for ww2 planes, 80s F1 race cars and current ones also. I encourage you especially to look up ww2 planes stuff because of the altitude change, they would put too big compressors for the sea level and thanks to pre compressor throttle they coud run at that sea level but have more power up top. As for F1 cars they did that to eliminate turbo lag by having turbos run in vacuum so they would run at high rpm always. Only con is that oil seals are made to work under pressure so you would burn some amount of oil at closed or partially open throttle but on your case i dont see an issue with that.
Good idea i saw a video about russian swirl throttle by maisteer and was wondering why body is using it anywhere i hope he answers this question because it seems like no branier.
That's so cool, I thought I knew a hell of a lot about turbo cars but I've never heard of this solution. Simple and brilliant
It's very inefficient. Some aircraft used this initially eventually dropping it.
@@chippyjohn1 they dropped it so hard current F1 race cars are using it
@@MiMi-ok7ch any source?
Another attribute of the EFR range and BW turbos in general is how robustly built the turbos are. The bearings are super reliable as well as the seals are can withstand extreme oil pressures and temperatures. There's a reason its the turbo of choice for so many street driven rotaries. Even used in Indy Car, and is now in the new ZR1 too.
I think the hardest thing to learn in any discipline is the right way to think about real complex problems from the high level, so you can actually apply all the lower-level textbook stuff. Thanks for sharing all your insights.
Agreed!
we need videos once the build is starting, im going to binge this for years to come
Kinda, that stuff comes on like a switch and can get explodey if done wrong or the system malfunctions. I like it though and is next on our list to use after switching twin scroll and regular antilag
A question, you have been speaking about running the engine on the dyno a couple of times. Since you are going to run it at altitude. Do the dyno shop have equipment to reduce the air pressure to what you are going to run at?
Where I’ve been dynoing my engines the shop have a big centrifugal Kompressor that they attach to exhaust, inlet, crankcase and all the “holes” that is significant to simulate different altitudes
You make a very good point. Robin please let us know.
Huh why? That's stupid. He has to retune it anyways
teams sometimes take a trailor mounted wheel or hub dyno and take it up the mountain and map the car like that..
Simulating aire pressure is easy enough, you can restrict the inlet, and yes you can attach a large compressor yo the exhaust to simulate low pressure altitude. The difficult part is temperature at the inlet which is a large factor of density. Trying to lower the inlet temperature to what you may see at altitude is difficult.
That sounds trick! We have a process, running at different altitudes that gets us close enough come running on the mountain
Love the Q&A at the end!
Thank you for sharing your hard-earned experience.
My pleasure!
3:26 The power under the curve.
Super interesting. Would be fun to see how the area on the compressor map used area for your application moves depending on altitude. More editing needed ofc, so less car-engineering. I get your tradeoff. Keep it up!
My initial thought was VNT. I had one on my golf (mk1 1300!!) in about 2000(ish). The performance really was staggering. Lag and boost threshold of a T2 but good for well over 300.
That turbo looks pretty trick. Materials certainly have moved on since I was playing with them.
Great stuff.
VNTs can't take a lot of heat. Might work well in a remote setup though.
@@heem6619 that was always a concern but never a problem. Ran them on all sorts - R5, scooby and even a pair on a VR4 (had fun getting the plumbing right!). Never had a failure.
Hi Robin, would you consider experimenting with 2 stage supercharging like on WW2 Rolls Royce Merlin?
I need to read into this particular setup and learn more!
@thesendyclub please help do so!!! there is also 'turbo-supercharching' which is 1st stage super charger and a 2nd stage turbo like on Alison v1710 and Pratt & Whitney R2800 engines
@@thesendyclub please help do so!!! there is also 'turbo-supercharching' which is 1st stage super charger and a 2nd stage turbo like on Alison v1710 and Pratt & Whitney R2800 engines
Wouldn’t it be an easier anti-lag strategy to use nitrous intermittently (since the rules don’t prohibit its use)? You can use as much or as little as you want and it’s very effective at increasing low speed torque production even below the boost threshold RPM / load…
Have you considered making use of a rocket anti-lag system to help deal with turbo response? Would be awesome to hear your thoughts on this type of system.
Would you run a cvt? you would always stay on boost. If you can find one thats strong enough.
No one would like it - but a well developed CVT would rule the roost on the mountain
It would essentially impossible to find any commercial CVT capable of running this HP, at a weight he would accept.
I think it would be technically possible, but would cost a lot in development time.
I can picture some very creative solutions splitting torque on planetary’s, and using hydraulic or electric motors to modulate the speeds of each the planetary components. AGCO does this in high HP tractors with remarkable efficiency, the challenge would be converting it from a high torque system to a higher RPM light weight system.
th-cam.com/video/dgtIKMAjvFI/w-d-xo.html
Something like this would not require the extra weight of batteries, but would still be significantly heavier than a conventional gear box.
@OwenDarrach Williams were developing a cvt in Formula 1 back in th 80s or early 90s but they never used it because it got banned before they got to use it. It's a shame they didn't get to develop it more because they might have done a better job at it than the ones car manufacturers are doing now.
@@Paul-ik8fm I have heard about that, but as far as I have heard they were never able to have the compression “belt” last long enough. Banned or not I was under the impression it never matured enough to actually race after considerable development. Most of what I read also indicated they had they were testing at closer to 850 hp, adding another 150 hp would have only made the challenges more prevalent.
There are lots of other ways to accomplish the CVT effect, was my main point. The AGO concept would theoretically mean the electric system could be very small relative to the total HP.
Most of the easy to find content on that thing lacks a lot of technical / engineering depth. If you have a comprehensive source I would love to read more on it.
since this is a pikes peak and timeattak car, will you ever try a nordschleife lap?
If they let me...
@@thesendyclub you would need a roof wich i dont know if u have not but for the nordschleife u need a roof.
On the twin scroll turbo elmer racing makes a turbo collector that has a wastegate on one scroll pre turbo to have the same effect as the flap would have, they rate it to 1000hp too
Thank you for the heads up, exactly what we want!
I so wish there was a videogame about designing and racing a hillclimb monster
oooh that would be really fun. probably very hard to do realistically, but id love to play that.
@@playyourturntodieatvgperson I mean it wouldn't have to be 100% accurate as it should be playable half an hour at a time.
But it may be more feasible by giving it a basic modeller for bodywork, chassis, suspension and engine, and few simple validation tools that write the components files. So it doesn't have to simulate bodies like BeamNG but it still requires some craft to come out with a frame, the headers, the wings, etc. Either starting from a fictional production car or engine, or by scratch
This is one of the reasons piston aero engines were often turbo-supercharged, because boost targets were sometimes unachievable at altitude with turbocharged exhaust mass air flow.
OEM design a cavity in the manifold on cold side to mitigate pulsing.
Great video! What’s your plan for controlling the turbo speed? Are you considering using something on the cold side, like a more adjustable blow-off valve, similar to what’s used in drag racing, to improve spool time and refine power delivery more accurately?
Can't wait to see this thing in metal and on the mountain 🔥🔥🔥
Maybe more topical for another video but what do you think of the Enviate aero concept/overall platform concept? How constrained is the current concept by tire and wheel loading?
Will cover in the next video!
One of the manufacturers is using a compressor to charge a cyl with compressed air for anti lag might b a bit parasitic unless electrically driven
I liked and subscribed!
Are there any aftermarket electric turbos coming on the market yet? I mean the kind like I believe Porsche are using where there’s an electric motor sandwiched between compressor and turbine to assist with spooling up during shifts and low RPM times?
well the racecar won't be a hybrid, so i think it wouldn't really be worth it to use an eturbo. adding in all the necessary electronics would add a lot of weight on a pure combustion car
Yeah but I figured a battery sized for just spooling an e-turbo could be much smaller than the size needed for vehicle propulsion.
@@markmaher665 yeah it can be, but there are still dificulties, i watched a good video on this let me go find it
Turbo's made from pure Unobtainium might be the solution? Just avoid the ones made of Moronium. 😀
Hail the algorithm!
😊
Yeah, but the one in this bastard's head.
Yeah, but one in this legend's head.
Great video, thanks for sharing. One query, for open exhaust systems with aftermarket turbos with integral wastegates, those can sometimes have trouble maintaining boost control at higher rpm. Are you confident that the integral wastegate of your selected turbo will have enough flow potential to adequately control boost at high rpm?
It's worked on the Wolf, based on our data it should be good to go. We are running quite high boost so boost creep isn't such an issue
Is it possible to use a restrictor on the dyno to simulate the top of the mountain for testing?
Yes, it doesn't get you all the way there as it doesn't change the pressure the exhaust sees.
Only as a thought sort of questions but where do you decide to start with something and do you do it in steps or do you get a grand plan then try and execute it at once?
Could you talk about your anti lag system? I saw a video from Stav-tech where he added an throttle body on the intake of the turbo housing. To help prevent the turbo from slowing down. And he found that the responce time really decreased! My question is if you know this concept, and if you have Thaught about it or have some thing better in mind. I find this really interesting and not talked about enough. Great video again! :)
Yes, will cover this in an upcoming vid
Hey Robin, was there consideration of a hot V setup?
With your custom built* motor, would there be the possibility to effectively swap the heads? Obviously would need a new block to match water and oil passages, but would that be un-feasible? Would the weight savings (less exhaust piping, more CF intake piping) be too overshadowed by complexity?
Electric motor, controled by the ECU assisting the turbo could help the turbo spool up at the lower rev range, simular to a power assist steering.
The latest Porsche design does this and has some major emissions benefits. The excess compressed air is used to keep the catalytic converter happy at stoic under all loads and RPMs. That way the engine can run rich and make power without an emissions penalty.
I don’t think it would be worth the weight penalty or complexity on this Pike’s Peak car.
Is a compound turbo set up for both low end quick spool and high-end power to complex and unreasonable on the mountain?
Edit: I see the variable housing turbo accomplishes similar with less complexity.
The diesel record is held by a Radical with a triple compound turbo blown 1.9TDi.
Compounds on a gas engine, it takes really high boost. You only get so much exhaust energy, that energy needs to be split between the two turbos. Most gas engines will not be able to utilize a compound set up until it's very high h.p. (north of 4o psi in most cases )
@@Drew-i8g
@Drew-i8g Not true. Compound works fine on petrol engines, just run less boost. Less practical for lower pressure ratios though.
Have you asked borg if they can do a s368sx-r (13807105053) comp wheel in the 9274 assy? Similar compressor map with a smaller compressor. I have been trying to get a source for s258sx-r compressor wheels to throw one in a 7670 to no avail but I'm sure you wouldn't have any issues considering your collaboration with the 8370.
Does the gates twin-scroll turbo strategy fulfill a similar function to what compound turbos would without the weight/packaging penalties?
Hey mate , I really like the show and what you do it's great . Did you run traction control on the wolf and will you do it on the new car . Is there any benefit on the mountain with the power differences with altitude. I see a few drag and roll racers using it really well over here . Obviously the racing and cars are fields apart but just wondering if you use it and if so how you do it
Yes, we use traction control. Will do a full answer in the next video
Hi, regarding downforce and wings.
I haven´t really seen this solution yet and i ask myself why shouldn´t it work?
Passive DRS: so the splitter and the rear wing could be front pivoted and held up in the back by f.e. gas struts, so it "straightens" with faster airflow. Like that the downforce could be held kind of "costantish" at different speeds while also limiting the effects on ride height and wheel load at high speeds?
Is there a reason there is no such system widely used?
It is used, just not in high level motorsport because it’s banned although you have seen similar things with flexi wings in F1
Fast corners and braking from high speed with lower downforce doesn't make much sense, that's why DRS is active so it can be disabled once you near a corner.
This is what we are looking at using
for sea-level testing, are you going to use an inlet restrictor to simulate limited air on the mountain?
Just turn the boost down and rely on calcs
Its like building a turbocharged aircraft but actually more difficult. I only start with a low pressure ratio of 1.5 and rpm remains the same. Having a high pressure ratio and with variable rpm on a single compressor map is harder than most people realise. I was designing a high altitude aircraft to fly at 26km, and that needs 4 stage compounding for just 300kw with a crankshaft driven supercharger with a 600mm impeller.
Exactly, in reality it's a lot of work to make a compound setup work
I’m wondering if there are engine dump cells that are capable of controlling the ambient/atmospheric air pressure? Or if that would even be helpful for something like this.
There are, but top level stuff and $$$
@ fascinating. Would come in handy in Mexico City. Cheers
the bit about de-tuning the aero package at speed is very interesting, but how about a suspension linkage that reduces the angle of attack when the suspension is compressed? this would de-couple speed and down-force a bit and reduce the issues of drag and stress at high speed while preserving low-speed performance. probably forbidden in most regulations but for this particular event it might fly
Then you go over a bump and loose downforce.
Have you considered a variable geometry intake? There should be methods to do this without a significant weight penalty
Certainly there's a gain to be had in this part of the system. Wave physics make it very tricky and require a great deal of resources to get a small improvement. In other words, this is something more suited to a team with a much bigger budget. To keep from being spread too thin, you'd need at least 12 engineers working crazy hours and one of them would need to be a very experienced aero/thermo specialist. Maybe hard to believe, but at the peak of development some larger teams can have as many as 60 people working on drivability issues!
We've deleted the stock BMW one in this case. Small fry compared to the turbo effects
it looked like you considered parallel twin turbos. did you think about doing sequential or series turbos at some point and could you explain why a single is superior?
Our engine fitted the single turbos in the EFR range better. Covering compound in the next video
Would there be advantages to a hot V configuration with a large single turbo?
What fuel are you planning to use? Methanol would be good for performance but the volume you need to carry might be an issue. Nitrous ?
methanol could also save weight by not needing an intercooler. i expect that he will use some nitrous at the higher altitudes as well.
How are you determining what the maximum Fz is before mu drops so much that Fy no longer increases with increased normal load for the tire (Load Saturation). Do you have data from tire testing or guidelines from the manufacturer? Thanks!
Yokohama provide us with data, but it doesn't go high enough in load... It's more about keeping the car off the ground at Pikes. Those tires will take it
Thanks! 👍💪✌
Very long and drawn out question but, when considering building a vehicle for the first time without much prerecorded data, I understand that it is much more difficult to make decisions like this. How would someone like me go about finding a good guesstimate on power band and average rpm range/vehicle speed? Other people’s engine/gear ratios and car setup is different and may reach different speeds in the same straights or between corners. I find it difficult to understand where to sacrifice power for response and by how much especially with bespoke builds.😢I might be overthinking but just buying a different turbo might mean changing all piping sizes and possibly routing and weight and space and plumbing which can become a very expensive and consuming ordeal.
Having no wastegate on the turbo hot side and dump the boost cold side with a DBW throttle body will give the fastest response and ultimate boost pressure going up the mounting
Ash
This would likely result in overspeeding the turbo since you'd have no way to control its RPM.
@@Surestick88 it's being used like this in drag racing at the moment so they can get the RPM on the turbo off the line and down the track.
The other thing to do is put a Throttle body Infront of the turbo intake that closes when off the throttle making the compressor run in vacuum and not dumping the boost. That way the turbo keeps the RPM ready for snapping the throttle open and no turbo lag 😉
Was used in the 80s and still used like this now in F1
Force sensitive DRS.
Stick it on a spring?
Exactly!
Oooo, I got noticed!!!!
2003 Ford Focus RS WRC used a 45-liter titanium tank to store boost pressure and release it on demand. Does Pike Peak Rules have anything to say against it? 🤔
You can do that, lots of space required that I don't have!
Any consideration of compound supercharging systems (inc turbos) like they used to use in old WW2 planes and some rally cars? I'm guessing it's a case of complexity and weight isn't worth it
All hail the Sendy Club, and the weird YT algorithm.
I think a stock std s1000rr bmw goes to about 14500 rpm does the proto tipo go to that ?
We are stroked so limited to about 13,000rpm
How much data do you have logged for your previous runs up the mountain?
Seems like you could plug in the stats for any (or every) particular moment into Matchbot to simulate a previous run. Then experiment with engine and turbo parameters to compare power at each moment, then compare the curves. Throw in what you know about weight and gearbox, you can probably make an educated guess about run time impact.
I know different cars will have different runs, but I bet the throttle inputs and environmental conditions will be close enough that you could optimize against that previous run.
Like you say, we all want to plan for WOT max boost situations, which is a pretty small fraction of the run.
Imagine a dyno that runs the pedal input, and increasingly limits the intake pressure to simulate the mountain.
This is exactly what we do
Have you investigated boost storage like was secretly used in the WRC Ford 03?
Well it's essentially a huge pressure tank, if we're down to shaving single digit kilograms to save on weight I don't see it make sense on a car of that size
@@TMmodify pressurise the frame
I had to subscribe AGAIN. I think you are pissing off someone at a manufacturer. LOL!
Maybe compound turbo charging ?
Compound turbos could give you the full broad curve with the altitude change. They are still not well understood by many. I've been looking at doubles and even triples for aircraft up to 35k. The compounds will let you spool easy and still give you the flow up top. There's a couple guys that have mastered them in drag racing. I think both have been interviewed by Andre from High Performance Academy.
Team members have run these setups before on other cars, the single always ends up faster...
Less oxygen in the air means bigger intake to make up for the loss?
Intercoolers? Any plans to do stuff like, dry ice cooled system.
Might be more of a thing for the Diesels running their absolutely stupid boost level's.
I need you making a road legal hypercar
I don't know much about aerodynamics and I know even less about how permissive ground effect is, but if it operates on the basis of the air going faster under the car, then wouldn't it be the ideal place for air intake if you're running a turbo ?
The air going faster reduces its pressure because Bernoulli. You'd be pulling in air at lower pressure. There would also be the issue of all the dirt you'd have to filter out.
@@Surestick88 well yeah, it only creates downforce because the pressure is lower but I thought the goal of a ram intake was to be shaped in such a way that you convert that velocity back into pressure, although I guess at that point you gain nothing from placing it within the floor... The dirt on the other hand I completely forgot about
The ram air intake has to be in either free stream air like what you see in open wheel racecars, or where you get high pressure on the car aerodynamically, like in front engine race cars where they collect air density from the front of the radiator, for best results. You don't want foreign material in your race engine, that's for sure.
Then you lose power....
Beware the v band flange taking weight of turbine housing, your material properties are going to be different at 1000C and distort and leak if not considered. Balance the bracing needed vs flange type. But I’m sure you knew that
Learned that lesson already!
Single turbo makes more sense on a hot V V8
Awesome project
I am very surprised that a v-band turbine housing is the standard of the industry. Those T4/T6 flanges just make a terrible, hard to deal with joint. Tial used to make nice quality stainless v-band turbo housings- of course no doubt they weren't as efficient as the housings developed by the turbo manufacturers
Agreed!
Every time I watch this guy, I think he has to be Nicolas Cage’s secret luv child .
If you don't know them, take a look at Elmer Racing's spool valves
Very interesting! I am sending them an email, thank you!
@thesendyclub ☺️
Coming from the Honda motor in the Wolf and now to a V8, might you consider both of these elements combined in the future with the Neutron Engines K48 ? Personally i can see it being a hit if tested successfully
You have all that fuel, and all those computers, and anti-lag is *still* an unsolved problem. Boggles the mind.
You can get a turbo spooling pretty quickly, it's just that a single package is going to be a compromise every time. A system that would account for more rpm ranges would be heavier, more costly, more maintenance intensive, and more complex, and maybe that's what you want to avoid depending on the use case
Making an anti-lag setup that is motorsports-grade in quality with time AND money constraints is extremely difficult, especially if what you're dealing with is a hillclimb with huge changes in air density. Something that will last for a whole program without costing much and breaking stuff is gonna be difficult. Mind you that this team is not backed by a big manufacturer. Porsche excelled with their Pikes Peak program due to their excellent engine management on the GT2 RS.
Twin turbo is better suited mid range, singles are better suited top end power 🔋 👏
Normally yes, but the range of EFR turbos we were looking at, the single came out on top for mid range also!
Wot, no MGU-H? 😂
This comment is a session too late, but what about using a blown diffuser?
Tricky for us to simulate and not set fire to things. I'm leaving that to the F1 guys
@thesendyclub thanks for taking the time to reply - you are a scholar and a gentleman. I'm wishing you all the best with the new car
When running on a restricted development budget and one event a year. Would it not have been better to build a new wolf , and address any short comings as opposed to a ground up build which could potentially lead you down an engineering dead end . Or . Do you feel you have already done this . As an amateur that's developed my own competition machinery in the past. I feel that could be a less perilous approach
Less perilous but more restrictive. Plus I already have a Wolf with all the shortcomings figured out, so it would be more of the same
so....... still no rotary???
He already talked about the Wankel's inherent lack of thermal efficiency. More fuel to carry, just for it to dissipate into heat. It's also notoriously hard to cool conventionally with water, and depending on the oil to cool the engine down isn't really a good idea.
Still no, maybe next week.....
i don't get the point. call me stupid at will, but only if you can clearly elaborate and prove why you think so. so here is my thinking : find the peak toruqe of your engine running n/a. slap on a supercharger and gear it to produce at about say 1.2:1 pressure ratio at that rpm. what will happen is, a supercharger (positive displacment pump style) will not have a constant pressure ratio. as the engine volumetric efficiency changes, so will the pressure ratio of the supercharger. now you can use a larger turbo, have less lag as the supercharger will be sucking air in and help that thing to spool, you will hit your total pressure ratio sooner allso. say you need something like 2 bar or a pressure ratio of 3:1 . your supercharger will produce a least 1.2:1 , so the turbo doing just 2.5:1 pressure ratio in the worse case. that you get sooner. a larger turbo is less restrictive. a blower running on low boost ain't taking that much of power to run. you can bypass the supercharger, if you feel like, on the fly. you can whit some ingenuity do what aircrafts do and have a 2 speed supercharger, as you climb up it may or may not be benefical its not for me to decide.
it be a nice thing to see some talk about compound charging .
What you describe is a complicated, heavy system. A well sized single turbo is "good enough" and has been proven over and over to be faster on the mountain. One of our team members has made several compound systems on the request of teams. They now run single turbos. Diesel is a different situation though...
@@thesendyclub lets assume I digest the single turbo for the simplicity of Just being a single turbo. Assuming /rightfully/ that 2 or more smaller turbo chargers would only add complexity and yield about as much extra as a nothingburger.
That part is clear.
What never was clear , is whats complicated in 1 more pulley and a belt, and 1 more pipe. Specially when that yields a flatter tourqe cure and a greater usable rpm range , and additional power, and less lag , and ability/necessity of using a bigger and less restrictive turbo.
Thats the part what I would be interested in.
Surely diesel is different. Won't knock from higher boost.
That I give you.
But apart from the need to keep the boost from the system in check , why on earth would a blower + turbo be so big deal vs Just a turbo , from complexity point of view ?
Its a relatively simple device, a block that has a spinny thing that is driven by the engine via a belt , it has a port to suck from , and a port to blow to. You get yay amount of boost depending on 2 things , one is volumetric efficiency and the other is drive belt ratio.
In principle , the slower the blower runs the more efficient it is.
And that gives a lot of yeehaa.
DIESEL
Makes me think it'd be super cool to see an @AngeTheGreat collaboration running your car in his engine simulator
You could probably test on Umling La in Ladekh India in the Himalayas. Now closed to the public, paved, warmer climate, goes over 15k feet. Shhh, don't tell anyone
I'll keep it quiet ;)